1. Field of the Invention:
The present invention relates in general to an electric drive device and more particularly to an electric power steering device. More specifically, the present invention is concerned with an electric power steering device of a type that has an electronic control device installed therein.
2. Description of the Related Art:
In the field of industrial machines of these days, elements for controlling the machines are driven by an electric motor. Recently, a so-called mechanically and electrically integrated type drive device has started to be put into a practical usage in the field of the industrial machines, in which an electronic control device including semiconductor elements for controlling rotation speed and torque of an electric motor is integrally installed in the electric motor.
One of such mechanically and electrically integrated type drive devices is an electric power steering device used in a motor vehicle. When, in the electric power steering device, a steering wheel is handled by a driver, rotation direction and rotation torque of a steering shaft to which the steering wheel is connected are detected, and based on the detected rotation direction and rotation torque, an electric motor is turned in such a direction as to assist the driver's steering work. That is, a steering assist torque is produced by the electric motor upon turning of the steering wheel by the driver. For controlling the electric motor in the above-mentioned manner, an electronic control unit (ECU) is employed, which is installed in the electric power steering device.
Japanese Laid-open Patent Application (tokkai) 2013-60119 shows such electric power steering device. That is, the electric power steering device disclosed by the publication has an electric motor and an electronic control unit that are installed in a main body of the electric power steering device.
More specifically, the electric motor used for the electric power steering device has a cylindrical motor housing of aluminum alloy for receiving therein essential parts of the electric motor, and the electronic control unit used therefor is received in an ECU housing that is arranged at an axial end of the cylindrical motor housing opposite to the other axial end where an output shaft of the electric motor is provided. The electronic control unit in the ECU housing generally comprises a power circuit part, a power conversion circuit part that includes MOSFET (viz., metal oxide silicon field effect transistor) for controlling driving of the electric motor and a control circuit part that controls the MOSFET. Output terminals of the MOSFET are connected to input terminals of the electric motor through bus bars.
To the electronic control unit in the ECU housing, there is fed an electric power from a power source through a connector terminal assembly that is made of a synthetic resin and has lead wires installed therein. Information signals from detecting sensors are fed to the electronic control unit to detect current operation condition of the electric power steering device. When assembling the electric power steering device, the connector terminal assembly is passed through an opening of the ECU housing and connected to the electronic control unit, and then fixed to an outer wall of the ECU housing through connecting bolts.
In addition to the above-mentioned electric power steering device, the mechanically and electrically integrated type drive device is applied to electric hydraulic pressure control devices such as electric brake and the like.